Conventional active-oscilloscope probes typically provide an analog input for the registration of an analog signal. These probes further comprise an analog output for the output of the analog signal to a measuring device. An active circuit which processes the analog signal registered by means of a probe tip is included in the probe.
A large number of different physical measurement parameters can be registered by means of a probe. In view of this large number, it is necessary to use special probes for the different properties of the measurement parameter to be registered. For example, a different probe must be used for registering a high power signal than for registering a high-frequency signal.
In particular, the output signal provided by the probe is an analog electrical voltage which is processed by a measuring device connected to the probe. In the following, an analog signal is understood to be a time-continuous and value-continuous signal which, for example, provides an infinite and arbitrarily fine signal characteristic and can theoretically assume infinitely many values in the dynamic range. A digitization and recording of the analog signal to be registered is then implemented in the downstream measuring device, especially a digital storage oscilloscope or voltmeter. A specified trigger event is determined for the display of the signal. For the digitization of the signal, an analog-digital conversion is implemented in the measuring device. The signal is optionally conditioned through further analog circuits in the measuring device, for example, input amplified or decoupled. In particular, the measuring device offers extensive functions for triggering, recording, processing and display of the measurement signal to be registered.
It is disadvantageous in an arrangement of this kind that the accuracy of the probe is always limited by the accuracy of the measuring device. A probe which provides substantially better properties, for example, with regard to DC voltage component, accuracy, dynamic range or noise behaviour, is restricted by correspondingly poorer properties of the measuring device, so that the registered signal is impaired in an undesirable manner.
Alongside this, there also exist active probes with digital outputs in which a triggering, recording and processing of the analog input signal takes place in the probe itself. These recorded and digitised data are transmitted asynchronously via a digital interface to the measuring device for display. Such probes require a trigger signal from the measuring device in order to establish a time reference between the registered analog signal and the digitised signal to be transmitted. This trigger signal is specified by the measuring device and must be supplied to the probe via an external trigger-signal line from the measuring device. The provision of the trigger signal for the probe is effort-intensive and undesirable.
Furthermore, it is problematic in this context if measurements of several probes are to be processed in the measuring device in a synchronised manner. Different cable lengths and a poor accuracy of synchronisation lead to considerable measurement errors in the measuring device. Furthermore, the probe is very severely limited in its possibility for recording and processing the measurement data to be registered because of a small probe housing and its low maximum power consumption.
US 2006/026 9186 A1 proposes a probe for high-precision measurements which is connected to an oscilloscope. In this context, a digitization is provided in the probe in order to implement a setting and adjustment of the probe.
One object of the present invention is to provide a system and a method which registers analog measurement signals with high sensitivity and low storage requirement by means of a probe and communicates them to a measuring device. In particular, triggering and synchronisation of the signal to be registered should be provided in a simplified manner.